What Motivates Costless Altruism? Evidence from Laboratory Experiments

Costless altruistic behaviors are special altruistic behaviors that benefit others at no own cost. While in literature, the motivations of typical altruistic behaviors that generally involve own cost have been studied intensively, it is not clear yet, on the flip side, what motivations drive costless altruistic behaviors. In this paper, we examine how often costless altruistic behaviors happen and, if not always, the potential determinants of costless altruistic behaviors. Specifically, we conduct a series of human-computer experiments of repeated emotion game, separating the impacts of emotion and payoff on the occurrence of costless altruistic behaviors. We find that costless altruistic behaviors do not always happen, and the considerations regarding emotion (e.g., reciprocity) and self-payoff are two important determinants. Additionally, we find that rewarding altruistic behaviors and punishing unaltruistic behaviors lead to more costless altruistic behaviors, thus, can potentially promote the overall social welfare.